econet: remove compiler warnings

net/econet/af_econet.c: In function ‘econet_sendmsg’:
net/econet/af_econet.c:494: warning: label ‘error’ defined but not used
net/econet/af_econet.c:268: warning: unused variable ‘sk’

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Phil Blundell <philb@gnu.org>
Signed-off-by: David S. Miller <davem@davemloft.net>